Video compression technology is widely used in various products, such as digital set-top boxes (STB), HDTV decoders, DVD players, digital cameras, network multimedia video applications etc. There are various video encoding methods for compressing digital video content. There are already many video compression standards to standardize the various video encoding methods. Examples of these standards include MPEG-1, MPEG-2 (ITU-T H.262), MPEG-4, ITU-T H.261, ITU-T H.263 and ITU-T H.264.
Video encoding standards such as MPEG standards and the like generally achieve data compression through the use of various encoding techniques such as time and space prediction, transformation and quantification, entropy encoding or the like. Compression in a video encoder typically includes inter-frame prediction and intra-frame prediction to improve encoding efficiency. Inter-frame prediction uses time correlation between images of a video, while intra-frame prediction uses space correlation of pixels in images of a video.
Inter-frame prediction and intra-frame prediction are generally performed for pixel blocks.
For intra-frame prediction, it generally uses pixels already reconstructed to extrapolate blocks to be predicted. For example, as for any one of blocks to be encoded in the current image, it uses surrounding pixels that have been reconstructed to perform an interpolation in a certain direction, and takes the result after interpolation as a prediction block of the block to be encoded. Difference between the block to be encoded and the prediction block serves as a prediction residual, and the prediction residual is encoded after transformation and quantification.